CMS: Create local implementation of cloud migration for dev use (#86637)

* add developer mode property to config

* create cms stub

* cleanup

* implement and wire up gcom stub

* fix errors

* don't document the flag

pkg/services/cloudmigration/cmsclient/inmemory_client.go

@@ -0,0 +1,48 @@
+package cmsclient
+
+import (
+	"context"
+	"math/rand"
+
+	"github.com/grafana/grafana/pkg/services/cloudmigration"
+)
+
+// NewInMemoryClient returns an implementation of Client that returns canned responses
+func NewInMemoryClient() Client {
+	return &memoryClientImpl{}
+}
+
+type memoryClientImpl struct{}
+
+func (c *memoryClientImpl) ValidateKey(ctx context.Context, cm cloudmigration.CloudMigration) error {
+	// return ErrMigrationNotDeleted
+	return nil
+}
+
+func (c *memoryClientImpl) MigrateData(
+	ctx context.Context,
+	cm cloudmigration.CloudMigration,
+	request cloudmigration.MigrateDataRequestDTO,
+) (*cloudmigration.MigrateDataResponseDTO, error) {
+	//return nil, ErrMigrationNotDeleted
+
+	result := cloudmigration.MigrateDataResponseDTO{
+		Items: make([]cloudmigration.MigrateDataResponseItemDTO, len(request.Items)),
+	}
+
+	for i, v := range request.Items {
+		result.Items[i] = cloudmigration.MigrateDataResponseItemDTO{
+			Type:   v.Type,
+			RefID:  v.RefID,
+			Status: cloudmigration.ItemStatusOK,
+		}
+	}
+
+	// simulate flakiness on one random item
+	i := rand.Intn(len(result.Items))
+	failedItem := result.Items[i]
+	failedItem.Status, failedItem.Error = cloudmigration.ItemStatusError, "simulated random error"
+	result.Items[i] = failedItem
+
+	return &result, nil
+}